LAUSR

A phosphorus/silicon flame retardant, MVC-DOPO, was synthesized from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 2,4,6,8-tetra-methyl-2,4,6,8-tetra-vinyl-cyclo-tetrasiloxane (MVC) via addition reaction. Its flame-retardant effect on polycarbonate (PC) was investigated. The phosphorus/silicon flame retardant increased the limited oxygen index and UL-94 rating and reduced the heat release rate and total heat release of DOPO-MVC/PC composites during combustion, indicating the excellent flame-retardant effect of MVC-DOPO on PC. MVC-DOPO inhibited the burning intensity of PC material in the gaseous phase and promoted the formation of a more viscous residue in the condensed phase. Through releasing phosphorus-containing pieces and phenoxy radicals from the phosphaphenanthrene group, MVC-DOPO quenched the combustion chain reaction in the gaseous phase; through promoting formation of a more viscous residue and a dense char layer from the main actions of the cyclotetrasiloxane group, MVC-DOPO reduced fuel release and generated a barrier effect in the condensed phase. Hence, MVC-DOPO effectively exerted a flame-retardant effect on PC material in both the gaseous and condensed phases during combustion. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45815.